1. Field of the Invention
The present invention relates to a sodium vanadium oxide-based anode material for a sodium ion secondary battery, a preparation method thereof, and a sodium ion secondary battery having the same.
2. Discussion of Related Art
A conventional vanadium oxide-based anode material has been applied to a sodium ion secondary battery in some preceding researches. However, its application is limited to a cathode material, and in most cases, a lithium vanadium oxide-based anode material mainly for a lithium ion secondary battery has been prepared by performing pyrolysis with precursors such as lithium carbonate (Li2CO3) and vanadium oxide (V2O3) in a pure nitrogen atmosphere.
Specifically, conventional technologies relevant to a lithium vanadium oxide-based anode material for a lithium ion secondary battery include a method for mixing precursors such as Li2CO3, and V2O5 with an organic acid such as (COOH)2 and plasticizing a mixture (Korean Patent Application No.: 2007-0120974, SAMSUNG SDI Co., Ltd.), a method for preparing an anode material using crystalline vanadium such as LiNiVO4 and LiMnVO4 (Korean Patent Application No.: 2004-0056699, Korea Electrotechnology Research Institute), an anode material expressed by LiaMgbVOc (0.05<=a<=3, 0.12<=b<=2, 2<=2c−a−2b<=5) (Japanese Patent Laid-open Publication No.: 2002-216753, Sumitomo Metal Ind. Ltd.), a method for preparing a lithium vanadium oxide-based anode material by a sol-gel method using lithium salt and vanadium salt (Korean Patent Application Nos.: 2007-0037983˜0037988, SAMSUNG SDI Co., Ltd.), a method for preparing an active material precursor by mixing lithium salt, vanadium salt, and additive salt with a hydrothermal solvent and a method for preparing an anode material by performing reduction and calcination of the active material precursor (Korean Patent Application No.: 2007-0073377, SAMSUNG SDI Co., Ltd.), a method for preparing an anode material expressed by LiaMgbVOc (0.05<=a<=3, 0.12<=b<=2, 2<=c−a−2b<=5) or a lithium vanadium oxide-based anode material including an oxide expressed by Ce0.7Zr0.3O1.9 (US Patent Laid-open Publication No.: 2008/0241688), a preparation method using a surface treatment for coating a surface of a lithium vanadium oxide-based anode material expressed by Li1.1Ti0.1V0.9O2 with an inorganic oxide such as SiO2 (US Patent Laid-open Publication No.: 2008/0118840), a method for preparing an anode material by mixing lithium vanadium oxide and additives such as ZrO2 and Y2O3 (Korean Patent Application No.: 2007-0120978, SAMSUNG SDI Co., Ltd.), and the like.
As described above, many kinds of materials have been developed as a lithium vanadium oxide-based anode material for a lithium ion secondary battery until now, and since the lithium ion secondary battery market and industry are anticipated to be rapidly expanded, the demand therefor is expected to greatly increase. However, lithium as an essential metal for synthesizing an electrode material or relevant compounds do not exist in Korea, and thus all of such resources have been imported from abroad.
Therefore, as for a country with lack of natural resources like Korea, development of a new alternative anode material is needed. The present invention provides a sodium vanadium oxide-based anode material that is an anode material using sodium as a means for replacing such a lithium resource.